After all, you gotta drink something during your “free” cruise. Extra charges are port taxes and all government fees but also gratuities, drink packages and wifi fees if one wishes to purchase such incidentals. It means that the base fare for this cruise will be zero, but that extra charges still apply.
More active players also receive such offers onboard the cruise or through their membership as an annual perk that can be booked through the casino liaison similar to the one described above. Often times people have already forgotten all about it until such an offer arrives in their email or mailbox.
Membership in the Blue Chip Club, Celebrity Cruises loyalty program for the Fortunes Casino is usually dependent on the previous play activity and a sign-up.